Method for preparing aluminum scandium intermediate alloy through molten salt electrolysis of chlorine salt oxide system

Abstract

The invention discloses a method for preparing an aluminum scandium intermediate alloy through molten salt electrolysis of a chlorine salt oxide system. Scandium oxide serves as a raw material, CaO orMgO is added in a chloride fused salt electrolyte composed of a NaCl-CaCl2 or KCl-CaCl2, electrolysis raw material Sc2O3 is added, a chloride-oxide mixed fused salt electrolyte is composed, liquid aluminum serves as a cathode, graphite serves as an anode, direct current is led for electrolysis under the condition that the temperature ranges from 670 DEG C to 780 DEG C, the current density of theanode is 0.5-1.5 A / cm<2>, the electrolysis time ranges from 4 h to 10 h, and the liquid aluminum scandium intermediate alloy is obtained on the cathode at the bottom of an electrolytic cell. The method has the beneficial effects that the technology is simple and convenient, the production cost is low, the product purity is high, continuous production is easy, and a reducing agent does not need tobe used. Meanwhile, in the electrolysis process, the liquid aluminum scandium intermediate alloy is obtained on the cathode at the bottom of the electrolytic cell, the anode discharges CO2, generationof other harmful gases is avoided, and serious pollution to the environment is effectively reduced.

Description

technical field [0001] The invention relates to the technical field of preparation of an aluminum-scandium master alloy, in particular to a method for preparing an aluminum-scandium master alloy by electrolysis of a molten salt of a chloride oxide system. Background technique [0002] Scandium is a rare earth element, and it is the strongest modifier for the grain structure of cast aluminum alloys and the most effective recrystallization inhibitor for processed semi-finished products. Grain refinement, inhibit recrystallization, significantly improve the strength, toughness, welding and corrosion resistance of aluminum alloy. Scandium-containing aluminum alloys are widely used in aerospace industry, military industry, civil industry and other fields because they can greatly improve the comprehensive performance of traditional aluminum alloys. However, because scandium has the highest electronegativity among rare earth metals, its chemical activity is extremely high, and its...

AI Technical Summary

Problems solved by technology

However, because scandium has the highest electronegativity among rare earth metals, its chemical activity is extremely high, and its melting point is as high as 1541°C, which is quite different from the melting point of aluminum at 660°C. It is not easy to mix evenly when directly melting aluminum-scandium alloys, and the formed aluminum-scandium compound crystals Coarse particles and severe segregation; in the production process of industrial aluminum-scandium alloys, scandium must be added in the form of aluminum-scandium master alloys, so aluminum-scandium master alloys are key raw materials for the production of industrial aluminum-scandium alloys

[0003] The preparation methods of aluminum-scandium master alloy include pair mixing method, metallothermic reduction method and molten salt electrolysis method. Among them, molten salt electrolysis method has the advantages of simple process, low production cost, easy continuous production, and no need for reducing agent, etc., but it is difficult to be used. It is used to produce pure metals with a melting point higher than 1000°C. When liquid metal Al, Mg or Zn is used as the cathode, the corresponding alloy can be prepared by depositing alloy elements on the cathode.

In the fluoride molten salt system, with Sc 2 o 3 When the Al-Sc master alloy is prepared as raw material, the temperature of the fluoride molten salt electrolyte is usually high, which seriously corrodes the equipment and electrodes, and the Sc 2 o 3 Low solubility in the electrolyte is not conducive to the smooth and efficient operation of the electrolysis process for a long time

At present, the electrolyte composition used in the electrolysis of aluminum-scandium master alloys in the chloride molten salt system is mainly LiCl / NaCl-KCl-ScCl 3 , in the process of electrolysis, control the appropriate conditions, so that Sc 3+ It is reduced to a simple metal on the cathode and alloyed at the same time to obtain an aluminum-scandium intermediate alloy. Since the electrolytic raw material is scandium chloride, Cl on the anode - It is oxidized to generate chlorine gas, because there is no good way to use the generated chlorine gas, it is easy to cause serious pollution to the environment, and the raw material ScCl 3 The preparation process is long, the equipment is complicated, and the production cost is high